Animals, many in central Europe, initially (4)
I believe the answer is:
mice
'animals' is the definition.
(mouse is a kind of animal)
'many in central europe initially' is the wordplay.
'many' becomes 'm' (Roman numeral for a thousand).
'initially' indicates taking the first letters.
The first letters of 'in central europe' is 'ice'.
'm'+'ice'='MICE'
(Other definitions for mice that I've seen before include "eg Mickey and Minnie" , "Squeaking rodents" , "Computer controls" , "Surfers click with these" , "They'll play when the cat's away" .)